Updates & Press

Blog #6 - Feb. 2018What is a Tier 1 Environmental Impact Statement?What Issues Are Considered in an EIS? An Environmental Impact Statement, or an EIS, is a type of assessment required by the National Environmental Policy Act (NEPA) for federally funded or regulated projects. Of the different types of documentation, an EIS is considered the most thorough and considers all possible impacts of a proposed project –positive and negative – for many different resources. An EIS requires a Purpose and Need statement, which outlines why the project is needed and what the project hopes to achieve. From here, the study team identifies various options for the Interstate 11 (I-11) Corridor (referred to as corridor alternatives) that meet this Purpose and Need. Information is gathered and analyzed for all alternatives, including a No Build alternative (or, a “do-nothing” alternative) to determine which alternative best meets the project’s Purpose and Need while causing the least negative impacts on the built and natural environments. When adverse impacts are predicted, the EIS would identify strategies to avoid, minimize, or mitigate impacts. Major resource areas are analyzed.An EIS provides the federal agencies with the necessary information to make a decision regarding the proposed project and helps determine the potential consequences that could result from the project, what impacts can be mitigated, and which alternative best fits the Purpose and Need. How Were the Alternatives Defined?For the I-11 project, an Alternatives Selection Report (ASR) was published in December 2017 to document the development, evaluation and screening of a variety of corridor options from Nogales to Wickenburg. The ASR incorporated ideas and preferences on corridor options from local government agencies, tribes, stakeholders and the public. The ASR provides the basis for determining the alternatives to be evaluated in the Tier 1 EIS, which will analyze both Build Corridor Alternatives (i.e. alternative corridors from Nogales to Wickenburg that could move forward to construction), and a No-Build Alternative (i.e., do-nothing option).How Does a Tier 1 EIS Differ From a Traditional EIS?The I-11 Corridor study team is in the process of completing a Tier 1 EIS. A Tier 1 EIS covers the same subject matter as a project-level EIS, only on a much more general scale. Typically, a Tier 1 EIS is used when funding has not yet been identified for a project or for managing the NEPA process across a large geographic area, such as the I-11 Corridor. A Tier 1 EIS involves technical analysis completed on a broad scale and is therefore an effective method for identifying existing and future conditions and understanding the comprehensive effects of the project on the region. It provides the groundwork for future project-level I-11 environmental and technical studies.A Tier 1 EIS allows the study process to move forward with no identified funding, while still laying the groundwork for where the corridor alternatives could be located. Project-level or Tier 2 environmental studies and identified funding sources would be required to advance construction of the project, which could occur in phases as funding is available. During Tier 2 studies, more detailed project elements would be defined and assessed, such as the specific alignment (the identified route) and the location of traffic interchanges.

For more information about the ongoing Tier 1 EIS, check out our latest fact sheet, which is published in both English and Spanish.